Tremec TKX first cuts

I will say I did find this. Hurst TKX, TKO Crossmember fits 67-76 MOPAR A-Bodies – Hanlon Motorsports
It's a strictly bolt on, although I'm not sure if that's a good idea either. I would think a weld would be stronger.

Yup, I've seen that! I previously saw it on the Holley website. That would do a perfect job. Cons there are the cost, and size. It would require some serious cutting of the tunnel, because it also works for the TKO which is a tank compared to the TKX. BUT, it would perfectly replace the factory part, if not make it stronger since that piece is thicker steel (I know it looks thin, but the factory stamped steel is even thinner). I would argue a weld is not even necessary, but convenient to avoid clunking while driving.